Senator Wendy Davis, a Democrat from Fort Worth, speaks as she begins a filibuster in an effort to kill an abortion bill. Photograph: Eric Gay/AP

A Texas senator, Wendy Davis, has launched a marathon filibuster of an abortion bill that would severely restrict abortion access in the state.

To be successful, Davis must talk for 13 hours, during which she will not be allowed to sit, lean or take any breaks to go to the bathroom or eat. She is only allowed to stop speaking when listening to questions.

The Democrat senator is attempting to prevent the stringent bill from reaching the desk of Texas governor Rick Perry. The bill would ban abortion at 20 weeks gestation, place limits on abortion-inducing drugs and introduce other restrictions that advocates say would close 37 of the 42 clinics that provide abortions in the state.

The Texas House version of Senate Bill 5 passed on Monday morning, after major stalling by House Democrats. Davis's filibuster began at 11.18am CDT on Tuesday. She has argued her case by reading letters from women and doctors who would be impacted by the bill and speaking with politicians from both sides of the aisle.

Reproductive rights advocates are especially concerned with the bill's restrictions that would require abortions be performed in ambulatory surgical centers and would require physicians that perform abortions to have admitting privileges at hospitals within 30 miles, posing difficulties for women living in rural areas.

You can watch a live stream of the filibuster here:

10.30pm CDT update:

With less than two hours to go before the midnight deadline, the senate public gallery has filled up. A third point of order has been levelled against Davis, which, if sustained, would mean block the filibuster.

Jeers of outrage and chants of "let her speak" filled the senate as it was announced the third point of order was sustained.

Democrat senators have raised a number of questions over the process in an apparent attempt to delay a vote on whether to end the filibuster.

As the tension mounted, the number of people watching the live stream shot up to more than 100,000.

Hundreds of activists arrived in Austin to see through Davis' final hours. Local media reported a line to get into the chambers stretching three floors.

US president Barack Obama earlier tweeted his support for Davis.

"Something special is happening in Austin tonight," Obama wrote, adding the hashtag #standwithwendy, which was trending worldwide on Twitter.

Davis began her protest by telling the house she was "rising on the floor today to humbly give voice to thousands of Texans".

"What purpose does this bill serve? And could it be, might it just be a desire to limit women's access to safe, healthy, legal, constitutionally-protected abortions in the state of Texas?"

As the hours have progressed Davis has filled in the hours by making her case against the bill, and reading from the testimony of women and doctors who would be affected by the passing of Bill 5.

Davis is a rising Democratic senator. AP reports Democrats chose Davis to lead the charge against Bill 5 due to her background as a woman who had her first child at 19 and went on to graduate from Harvard Law School.

11.45pm CDT update

With only 15 minutes to go before the deadline, Democratic senators attempt to run down the clock with various procedural questions, as crowds build up outside the debating chamber.

12 midnight CDT update

Midnight has come and gone without a vote on the bill, which means, under normal rules, that it should fail. But nothing has been clear in this story so far. There were extraordinary scenes towards the deadline: just after 11.45pm, when Democratic senator Leticia Van de Putte asked what a female member had to do to be heard over a male senator, the public gallery erupted.

Amid nearly 15 minutes of sustained cheering, the senate president was unable to call the session to order.

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